American Mineralogist, Volume 88, pages 938–939, 2003

0003-004X/03/0506–938$05.00 938

Mr. President, members of the Society, and guests:This is the most important moment in my scientific life. I

thank all who were involved in choosing my name for this in-valuable honor; and I thank you, Pete, for finding such kindand thoughtful words in your introduction.

Yes, it was a difficult time, which Peter and I—both of 1930vintage—were born into. But with the humanistic attitude thatPeter Wyllie and so many American friends showed, even thedefeated former enemies were able to participate in a develop-ment of the world which—in its grandeur of progress—hasnever happened before, and may never happen again. It is myconviction that our generation, at least in Europe, is the mostblessed one that ever lived.

The early post-war years in Germany were indeed burden-some. But at least we learned that only hard labor could lead toimprovement. As a child in a big city, I was suffering fromallergies. The doctors told my mother that I should not spendmy life in offices and laboratories but always close to nature:So, I was to become a forester. But after the war, when all theestablished foresters from the former eastern parts of Germanymigrated westward, there was no chance for me. Instead ofstudying forestry I started geology, with the intention to domuch field work. As it turned out, however, I became an ex-perimental petrologist ending up in laboratories and offices afterall. And the allergies remained.

The universities of Erlangen and Munich that I attendedwere slowly recovering from war and Nazi terror, and they werepoor. Our education suffered from severe lack of instrumenta-tion. So, I could study these mysterious cordierite-bearinggneisses, which I had collected in the Bavarian Forest for mythesis, only with the petrographic microscope. The generalopinion was that all such high-grade metamorphic rocks wereof Precambrian age. When I, more intuitively than from hardfacts, argued for a younger, Hercynian age of at least some ofmy gneisses, nobody took me seriously.

An important event in my career occurred just before ob-taining my Doctor’s degree. My supervisor at Munich, GeorgFischer, asked me to give a seminar reporting on four papersfrom the Geophysical Laboratory in Washington, D.C., whichhe had just received. Although I really had to struggle with thetext, these articles were an eye-opener to me: This was the wayto do research on rocks and minerals! Because of my excite-ment, Georg Fischer kindly wrote to one of the authors, FelixChayes, asking about any chances for me at this Laboratory.Three weeks later, I sat trembling in an Amsterdam hotel hallbeing interviewed by Dr. Abelson, the Director of the Geo-physical Laboratory. There was this sudden and harsh ques-

tion: “Do you work hard?” I could just stammer: “I try to.”So, in 1958, I became the first post-doc from Germany at

the Geophysical Laboratory. Dr. Abelson gave me one week tointroduce myself to the whole Staff. Then it was up to me todecide with whom I wanted to work. What generosity! I hadthe good fortune that Hat Yoder was also very interested in themineral cordierite, and—above all—that he took on the onus ofteaching me how to work experimentally, and how to think as aphase petrologist. I was allowed to move into his office where Ihad the best of tutoring a young greenhorn could wish for.

The research was so fascinating and had so many differentfacets, that, after four years, people called me Mr. Cordierite. Al-though I disliked this, it became clear to me that we had set anexample—obviously for Hat it was not the first one. We had shown,for an extremely complicated rock-forming mineral, what kind ofphysical-chemical knowledge is necessary before one can deriveany meaningful conclusions concerning the origin of the rock. Inall my further work I tried to follow these guidelines.

Back home in Germany, I was again fortunate to be allowedto continue and expand this type of research. But I also had astrange experience concerning my former ideas about the ageof metamorphism in the Bavarian Forest. While still at theGeophysical Laboratory, my friends Gordon Davis and GeorgeTilton had been helpful in determining Rb/Sr biotite ages onsome of my rocks from this area. To my great satisfaction, theyall came out to be Hercynian! So, during the first official geo-logical meeting after my return to Germany in 1962 I reportedon these very first absolute mineral ages available for the wholeof the Bohemian Massif. The result was that the chairman ofthe meeting interrupted me, before my alloted time was over,

Acceptance of the Roebling Medal of the Mineralogical Society of America for 2002

WERNER SCHREYER

Professor Emeritus, Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität, D-44780 Bochum, Germany

PRESENTATION OF AWARDS 939

saying that this was now enough of this nonsense, and he or-dered me back to my seat. It was slightly comforting for theyoung frustrated geoscientist that a small revolution took placein the lecture hall afterwards. Moreover, this incident made myname (in whatever sense) known in German geoscientificcircles, certainly more than I had anticipated! But I decidedfrom this time on to concentrate fully on my experimental min-eralogical-petrological work. Now, everybody accepts that thelast metamorphism in the Bavarian Forest is of Hercynian age.

The experimental studies expanded even more after 1966, whenI became Professor at the new Ruhr-University at Bochum andreceived ample financial support for apparatus and personnel. Icould also recruit good students and found excellent colleagues,like my first Doctoral student Fritz Seifert, who shared, or evenexceeded, my enthusiasm. We became successful and known inthe world. One day, at an international conference, I enjoyed lis-tening to a conversation between two of the participants, one ask-ing the other: “Where the hell is this place Bochum?”

An important reason for our success was that—to my greatsurprise—the experimental efforts in the U.S. had declined con-siderably. Ironically, this was the second support I received fromAmerica. It was the time when thermodynamic calculations alonewere considered the most useful tool for understanding mineralassemblages in metamorphic rocks. There was—and is—a lot oftruth in this attitude, but by now we know that all this has to bebased on the best possible experimental data, and I still feel thatthe final critical test has to come from the experiment.

Starting in the 1970s it was a great pleasure for me to goback to the field as well and select mineralogical and petro-logical problems worldwide for detailed studies. My sabbati-cal stays at universities in South Africa and Australia were idealfor gaining the necessary field knowledge and collectingsamples. The basic idea was to relate these findings to experi-mental results, and this worked both ways. We found rocksthat duplicated seemingly strange experimental results, andthere were these enigmatic findings from nature that guided usto do specific experiments. Let me cite two examples.

Our 1964 experimental results on Mg-cordierite implied thatthis low-pressure mineral breaks down at high pressures intothe assemblage talc + kyanite, but this pair had never been foundin nature. Nearly ten years later, my colleague Kulke at Bochumshowed me a collection of rocks which he had sampled duringhis stay in Afghanistan. I could hardly believe it when I pickedout a talc schist with spectacular bluish crystals of kyanite. Thewhiteschists were discovered!

On the other hand, in a sample collected on a Bochum fieldtrip through Yugoslavia, we first discovered the assemblage oftalc with potassic white mica, phengite, in a metasedimentaryrock. Our experiments designed to study this problem showedclearly that this pair is characteristic for pressures prevailingonly below the Continental Moho, where a sediment shouldnever reside. And what a surprise: soon the same pair was foundas a widespread constituent in metapelites of the Alps!

Then came the incredible discoveries by our friends of so-called ultrahigh-pressure metamorphic rocks, when ChristianChopin—then working at the Bochum Lab—described coesiteand a series of strange minerals from the Dora Maira Massif inthe Western Alps, in rocks that had surely formed initially within

the continental crust. The absolutely unthinkable became a sci-entific fact: continental crust of our globe can be subducted atleast as deeply as 150 kilometers before returning back to theEarth’s surface. Let me emphasize this here: without the phaseequilibrium work of experimental petrologists and withoutmeticulous studies by those keen rock observers using the “old-fashioned“ petrographic microscope, this breakthrough in thegeological and geophysical thinking would not have happened.We cannot give up the basic petrologic concept of correlatingobservation and experiment, but we can now add modelling.

In this exciting world of metamorphism of crustal rocksunder mantle pressures, my interest in geochronology was re-vived, despite previous experiences. George Tilton at SantaBarbara very kindly invited me to spend my last sabbatical inhis lab and taught me how to prepare mineral and rock samplesfrom Dora Maira for isotope measurements to be done by him.That the pyrope crystals, previously considered to be productsof mantle material exclusively, clearly showed crustal isotopesignatures, that the ultradeep subduction must have occurredrelatively late in Alpine history, and that exhumation must havebeen a rather rapid process, all that increased the fascinationabout the newly discovered terrestrial mechanism even more.

Is it fortuitous that, after last year’s recipient, the giant Pe-ter Wyllie, I am the next experimental petrologist to be awardedthe Roebling medal? After the man who has conducted experi-ments on virtually any kind of igneous rock, I am really happy,in a very modest way, to represent some part of the metamor-phic realm, in nature and experiment.

Now, entering mineralogical heaven, I will meet again allthe heroes of my youthful days, earlier Roebling medalists likeC.E. Tilley, J.Frank Schairer, T.F.W. Barth, Paul Ramdohr, andFritz Laves. With all of them I had personal contacts and learnedfrom them, from the incredibly keen observer Ramdohr andfrom Frank Schairer at the Geophysical Lab with whom I coulddo melting experiments. His Bavarian descent, that was stillquite obvious to me, had created a particular attachment to him.In the Lab Frank told me: “Think like a silicate!” And when onone of the annual Lab field trips we were driving through won-derful scenery which we could not identify on our map, Frankmade the mysterious remark: “If you don’t know where to go,you can’t get lost.”

This sentence has been haunting me through all these years.It sounds like a terrible way of planning a scientific career. Yet,on second thought: is there not a lot of truth and philosophy inthese words? A young scientist cannot foresee what is going tohappen to him or her personally, e.g., regarding employmentchances, or even what the development of their scientific fieldwill be. They can only register carefully what nature, experi-ment, and literature tell them, and what they learn from theirpeers. Then they must ask the right questions, follow logicalthinking, and possibly intuition. If they are lucky, they maymake the elucidating discovery, without getting lost in the jungleof the imperceptible.

A good deal of this has happened to me over the years andis still happening. I thank all who supported me in my life: myfamily, my students, my colleagues, and friends at home and abroad.Thank you, Ed Grew for nominating me. Thank you Society, com-mittee, and reviewers, and thank you all for listening.